Grammar: Modal Verbs

A: Modals are auxiliary or the helping verbs which help add functions to sentences and also carry additional concepts. Modals have the following properties: 

• Negation: Auxiliaries take not or n't to form the negative, eg. cannot, don't, wouldn't. 
• Inversion: Auxiliaries invert with what precedes them when we form questions: [I will] see you soon ~ [Will I] see you soon? 
• Code: Auxiliaries may occur "stranded" where a main verb has been omitted: John never sings, but Mary does. 
• Emphasis: Auxiliaries can be used for emphasis: I do like cheese. Modality: they also express concepts such as possibility, obligation, certainty, anticipation and capability.

NeoTip
Option B is correct because 'Must' is used for logical conclusion while 'Will' is not used. 'Roads are wet. It will have rained last night' is wrong.

B: Lexical Verbs are the main vocabulary words while Auxiliary Verbs are the function words. Below, Auxialiary Verbs are bold and Lexical Verbs are underlined for quick understanding.

Her pace slowed and an ache spread from between her shoulders. Vapours swirled and banked; the light of on-coming headlights drained out of the car. [...] Sodium street lamps burned phosphorescent holes in the fog, but as she turned off Main Street to the cottage she noticed the one which illuminated the alley was out. She must be going fast to catch up with time. She looked tired and she must have walked a mile or so. She cannot go any where at the moment. She shouldn’t be alone on the roads like that. The roads can be dangerous. They will envelop her in their dark corners. She may be lost or she might be forced into a wrong turn. There is no time to think about these dangers. She has to go and dare go alone to find her lost mate. She must search and search for the dear one lost something.

C: Modal verbs are used for their modality serves different functions.

1. He must have missed the bus. Logical Conclusion
2. I must wash my hair.  Obligation
3. You must do as you are told. Obligation
4. You must be delighted. Logical Conclusion
5. He might win. Possibility
6. He can open the window. Capability
7. He can't come in.  Permission
8. He can't be in, there's no reply. Logical Conclusion
9. You can't know her very well.  Logical Conclusion
10. You mustn't do that. Moral duty
11. You've done it before, so it should be easy.  Obligation
12. You should do as you are told. Obligation
13. I'll open the door. Decision
14. That will be the postman at the door. Possibility
15. That may not be true. Possibility

Exercises

Correct the following sentences.
1. He is in trouble. I think, we will help him.
2. I use to play truant when I was a child.
3. Can I come in, sir?
4. May you come with me today for the movie?
5. Mr. President, can you comment on the present situation?
6. He can speak English well when he was six.
7. May I live a thousand years?
8. It is almost impossible. You may get this job.
9. What will I do now?
10. Her admission is okay. He should leave today.
11. Will I come along and help you?
12. His room light is off. He can have gone out.
13. We need to respect law.
14. I must wear a uniform at the office.
15. She says that you must go and see him off.
16. I think I have to go and see him.
17. They had better to leave early.
18. I always played football when I was ten.
19. Could he speak English when he was abroad?
20. Will we offer something?
21. This is a bad thing. They will give it up soon.
22. Have you better to do that again?
23. There is a message for me and I must go now.
24. You needn’t talk to elders like that.
25. He is a lawyer. He can be good at using words.